Exemplary embodiments of the present invention relate to an image correction method for a multi-projection system, an image correcting device for a multi-projection system, and a multi-projection system.
The related art includes multi-projection systems which can display one large-screen image by arranging a plurality of optical projection units (hereinafter, referred to as projectors) in the horizontal or vertical direction, or in the horizontal and vertical directions, respectively, and performing tiling projection of projection images onto a screen from the plurality of projectors. The tiling projection means a projection method allowing one large-size image to be displayed by arranging the projection areas of the plurality of projectors on the screen in a tile shape.
Since such multi-projection systems can display images with high definition and high brightness, it is expected that the multi-projection systems should be widely spread in the business field of movie theaters, art galleries, museums, seminar meeting places, meeting places, mini theaters, public institutions, business enterprises, etc. or in the household field of amusements, home theaters, etc.
In such multi-projection systems, it is necessary to project images (hereinafter, referred to as unit images) such that the unit images projected from a plurality of projectors should not be geometrically inconsistent. As a result, the related art includes a variety of techniques for providing consistency between the unit images projected from the plurality of projectors.
In the multi-projection systems of the related art, a technique of displaying projection images from adjacent projectors so as to have an area where parts thereof are overlapped on a screen (hereinafter, referred to as an overlapping area) has been put into practice.
In the related art, when the projection images are displayed on the screen so as to have the overlapping area, a geometric correction function between a display area in the respective projectors of image data projected from the respective projectors and a projection area of the respective projectors on the screen is calculated. Further, geometrically-corrected image data to be properly projected onto the screen are generated from the geometric correction function and the image data, and the geometrically-corrected image data are projected from the respective projectors.
At this time, insufficient accuracy of the geometric correction function in the overlapping areas among the projectors can generate defocused images in the overlapping areas, thereby largely damaging quality of the projection images in the multi-projection systems.
As described above, the related art includes a variety of techniques for improvement image quality in the overlapping areas when the projection images from adjacent projectors are displayed to have the areas where parts of the projection images are overlapped on the screen (hereinafter, referred to as overlapping areas). Examples thereof are disclosed in Related Art Documents Japanese Unexamined Patent Application Publication No. 9-326981, Japanese Unexamined Patent Application Publication No. 2002-72359 and Japanese Unexamined Patent Application Publication No. 2003-219324.
In Related Art Document Japanese Unexamined Patent Application Publication No. 9-326981, pattern images are projected onto a screen from a plurality of projectors, the pattern images projected onto the screen are photographed with a camera, and projection positions of the projectors are calculated on the basis of the pattern images obtained by photographing the original pattern images.
In Related Art Document Japanese Unexamined Patent Application Publication No. 2002-72359, pattern images are projected onto a screen from a plurality of projectors, the pattern images projected onto the screen are photographed with a camera, and a geometric deformation function between the projection images projected from the projectors and the projection areas on the screen is calculated on the basis of the pattern image obtained by photographing the original pattern images. In Related Art Japanese Document Unexamined Patent Application Publication No. 2002-72359, a method of dividing a projection area from a single projector into small areas and calculating a geometric variable function for each small area is disclosed.
In Related Art Document Japanese Unexamined Patent Application Publication No. 2003-219324, calibration pattern images are projected onto a screen from a plurality of projectors, the calibration pattern images projected onto the screen are photographed with a camera, and image correction data of the images to be projected from the respective projectors are calculated on the basis of the calibration pattern images obtained by photographing the calibration pattern images. The calibration pattern images disclosed in Related Art Document Japanese Unexamined Patent Application Publication No. 2003-219324 have markers or gradations and the image correction data are calculated using the center of gravity obtained from the brightness values of the markers or gradations.